/*
 * Copyright 2003,2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.cglib.core;

import org.springframework.asm.ClassVisitor;
import org.springframework.asm.Label;
import org.springframework.asm.Type;
import org.springframework.cglib.core.internal.CustomizerRegistry;

import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.Collections;
import java.util.List;

/**
 * Generates classes to handle multi-valued keys, for use in things such as Maps and Sets.
 * Code for <code>equals</code> and <code>hashCode</code> methods follow the
 * the rules laid out in <i>Effective Java</i> by Joshua Bloch.
 * <p>
 * To generate a <code>KeyFactory</code>, you need to supply an interface which
 * describes the structure of the key. The interface should have a
 * single method named <code>newInstance</code>, which returns an
 * <code>Object</code>. The arguments array can be
 * <i>anything</i>--Objects, primitive values, or single or
 * multi-dimension arrays of either. For example:
 * <p><pre>
 *     private interface IntStringKey {
 *         public Object newInstance(int i, String s);
 *     }
 * </pre><p>
 * Once you have made a <code>KeyFactory</code>, you generate a new key by calling
 * the <code>newInstance</code> method defined by your interface.
 * <p><pre>
 *     IntStringKey factory = (IntStringKey)KeyFactory.create(IntStringKey.class);
 *     Object key1 = factory.newInstance(4, "Hello");
 *     Object key2 = factory.newInstance(4, "World");
 * </pre><p>
 * <b>Note:</b>
 * <code>hashCode</code> equality between two keys <code>key1</code> and <code>key2</code> is only guaranteed if
 * <code>key1.equals(key2)</code> <i>and</i> the keys were produced by the same factory.
 *
 * @version $Id: KeyFactory.java,v 1.26 2006/03/05 02:43:19 herbyderby Exp $
 */
@SuppressWarnings({"rawtypes", "unchecked"})
abstract public class KeyFactory
{

    private static final Signature GET_NAME = TypeUtils.parseSignature("String getName()");
    public static final Customizer CLASS_BY_NAME = new Customizer()
    {
        public void customize(CodeEmitter e, Type type)
        {
            if (type.equals(Constants.TYPE_CLASS))
            {
                e.invoke_virtual(Constants.TYPE_CLASS, GET_NAME);
            }
        }
    };
    public static final FieldTypeCustomizer STORE_CLASS_AS_STRING = new FieldTypeCustomizer()
    {
        public void customize(CodeEmitter e, int index, Type type)
        {
            if (type.equals(Constants.TYPE_CLASS))
            {
                e.invoke_virtual(Constants.TYPE_CLASS, GET_NAME);
            }
        }

        public Type getOutType(int index, Type type)
        {
            if (type.equals(Constants.TYPE_CLASS))
            {
                return Constants.TYPE_STRING;
            }
            return type;
        }
    };
    private static final Signature GET_CLASS = TypeUtils.parseSignature("Class getClass()");
    /**
     * @deprecated this customizer might result in unexpected class leak since key object still holds a strong reference to the Object and class.
     * It is recommended to have pre-processing method that would strip Objects and represent Classes as Strings
     */
    @Deprecated
    public static final Customizer OBJECT_BY_CLASS = new Customizer()
    {
        public void customize(CodeEmitter e, Type type)
        {
            e.invoke_virtual(Constants.TYPE_OBJECT, GET_CLASS);
        }
    };
    private static final Signature HASH_CODE = TypeUtils.parseSignature("int hashCode()");
    private static final Signature EQUALS = TypeUtils.parseSignature("boolean equals(Object)");
    private static final Signature TO_STRING = TypeUtils.parseSignature("String toString()");
    private static final Signature APPEND_STRING = TypeUtils.parseSignature("StringBuffer append(String)");
    private static final Type KEY_FACTORY = TypeUtils.parseType("org.springframework.cglib.core.KeyFactory");
    private static final Signature GET_SORT = TypeUtils.parseSignature("int getSort()");
    /**
     * {@link Type#hashCode()} is very expensive as it traverses full descriptor to calculate hash code.
     * This customizer uses {@link Type#getSort()} as a hash code.
     */
    public static final HashCodeCustomizer HASH_ASM_TYPE = new HashCodeCustomizer()
    {
        public boolean customize(CodeEmitter e, Type type)
        {
            if (Constants.TYPE_TYPE.equals(type))
            {
                e.invoke_virtual(type, GET_SORT);
                return true;
            }
            return false;
        }
    };
    //generated numbers:
    private final static int PRIMES[] = {11, 73, 179, 331, 521, 787, 1213, 1823, 2609, 3691, 5189, 7247, 10037, 13931, 19289, 26627, 36683, 50441, 69403, 95401, 131129, 180179, 247501, 340057, 467063, 641371, 880603, 1209107, 1660097, 2279161, 3129011, 4295723, 5897291, 8095873, 11114263, 15257791, 20946017, 28754629, 39474179, 54189869, 74391461, 102123817, 140194277, 192456917, 264202273, 362693231, 497900099, 683510293, 938313161, 1288102441, 1768288259};

    protected KeyFactory()
    {
    }

    public static KeyFactory create(Class keyInterface)
    {
        return create(keyInterface, null);
    }

    public static KeyFactory create(Class keyInterface, Customizer customizer)
    {
        return create(keyInterface.getClassLoader(), keyInterface, customizer);
    }

    public static KeyFactory create(Class keyInterface, KeyFactoryCustomizer first, List<KeyFactoryCustomizer> next)
    {
        return create(keyInterface.getClassLoader(), keyInterface, first, next);
    }

    public static KeyFactory create(ClassLoader loader, Class keyInterface, Customizer customizer)
    {
        return create(loader, keyInterface, customizer, Collections.<KeyFactoryCustomizer>emptyList());
    }

    public static KeyFactory create(ClassLoader loader, Class keyInterface, KeyFactoryCustomizer customizer, List<KeyFactoryCustomizer> next)
    {
        Generator gen = new Generator();
        gen.setInterface(keyInterface);
        // SPRING PATCH BEGIN
        gen.setContextClass(keyInterface);
        // SPRING PATCH END

        if (customizer != null)
        {
            gen.addCustomizer(customizer);
        }
        if (next != null && !next.isEmpty())
        {
            for (KeyFactoryCustomizer keyFactoryCustomizer : next)
            {
                gen.addCustomizer(keyFactoryCustomizer);
            }
        }
        gen.setClassLoader(loader);
        return gen.create();
    }


    public static class Generator extends AbstractClassGenerator
    {

        private static final Source SOURCE = new Source(KeyFactory.class.getName());

        private static final Class[] KNOWN_CUSTOMIZER_TYPES = new Class[]{Customizer.class, FieldTypeCustomizer.class};

        private Class keyInterface;

        // TODO: Make me final when deprecated methods are removed
        private CustomizerRegistry customizers = new CustomizerRegistry(KNOWN_CUSTOMIZER_TYPES);

        private int constant;

        private int multiplier;

        public Generator()
        {
            super(SOURCE);
        }

        protected ClassLoader getDefaultClassLoader()
        {
            return keyInterface.getClassLoader();
        }

        protected ProtectionDomain getProtectionDomain()
        {
            return ReflectUtils.getProtectionDomain(keyInterface);
        }

        /**
         * @deprecated Use {@link #addCustomizer(KeyFactoryCustomizer)} instead.
         */
        @Deprecated
        public void setCustomizer(Customizer customizer)
        {
            customizers = CustomizerRegistry.singleton(customizer);
        }

        public void addCustomizer(KeyFactoryCustomizer customizer)
        {
            customizers.add(customizer);
        }

        public <T> List<T> getCustomizers(Class<T> klass)
        {
            return customizers.get(klass);
        }

        public void setInterface(Class keyInterface)
        {
            this.keyInterface = keyInterface;
        }

        public KeyFactory create()
        {
            setNamePrefix(keyInterface.getName());
            return (KeyFactory) super.create(keyInterface.getName());
        }

        public void setHashConstant(int constant)
        {
            this.constant = constant;
        }

        public void setHashMultiplier(int multiplier)
        {
            this.multiplier = multiplier;
        }

        protected Object firstInstance(Class type)
        {
            return ReflectUtils.newInstance(type);
        }

        protected Object nextInstance(Object instance)
        {
            return instance;
        }

        public void generateClass(ClassVisitor v)
        {
            ClassEmitter ce = new ClassEmitter(v);

            Method newInstance = ReflectUtils.findNewInstance(keyInterface);
            if (!newInstance.getReturnType().equals(Object.class))
            {
                throw new IllegalArgumentException("newInstance method must return Object");
            }

            Type[] parameterTypes = TypeUtils.getTypes(newInstance.getParameterTypes());
            ce.begin_class(Constants.V1_2, Constants.ACC_PUBLIC, getClassName(), KEY_FACTORY, new Type[]{Type.getType(keyInterface)}, Constants.SOURCE_FILE);
            EmitUtils.null_constructor(ce);
            EmitUtils.factory_method(ce, ReflectUtils.getSignature(newInstance));

            int seed = 0;
            CodeEmitter e = ce.begin_method(Constants.ACC_PUBLIC, TypeUtils.parseConstructor(parameterTypes), null);
            e.load_this();
            e.super_invoke_constructor();
            e.load_this();
            List<FieldTypeCustomizer> fieldTypeCustomizers = getCustomizers(FieldTypeCustomizer.class);
            for (int i = 0; i < parameterTypes.length; i++)
            {
                Type parameterType = parameterTypes[i];
                Type fieldType     = parameterType;
                for (FieldTypeCustomizer customizer : fieldTypeCustomizers)
                {
                    fieldType = customizer.getOutType(i, fieldType);
                }
                seed += fieldType.hashCode();
                ce.declare_field(Constants.ACC_PRIVATE | Constants.ACC_FINAL, getFieldName(i), fieldType, null);
                e.dup();
                e.load_arg(i);
                for (FieldTypeCustomizer customizer : fieldTypeCustomizers)
                {
                    customizer.customize(e, i, parameterType);
                }
                e.putfield(getFieldName(i));
            }
            e.return_value();
            e.end_method();

            // hash code
            e = ce.begin_method(Constants.ACC_PUBLIC, HASH_CODE, null);
            int hc = (constant != 0) ? constant : PRIMES[(Math.abs(seed) % PRIMES.length)];
            int hm = (multiplier != 0) ? multiplier : PRIMES[(Math.abs(seed * 13) % PRIMES.length)];
            e.push(hc);
            for (int i = 0; i < parameterTypes.length; i++)
            {
                e.load_this();
                e.getfield(getFieldName(i));
                EmitUtils.hash_code(e, parameterTypes[i], hm, customizers);
            }
            e.return_value();
            e.end_method();

            // equals
            e = ce.begin_method(Constants.ACC_PUBLIC, EQUALS, null);
            Label fail = e.make_label();
            e.load_arg(0);
            e.instance_of_this();
            e.if_jump(CodeEmitter.EQ, fail);
            for (int i = 0; i < parameterTypes.length; i++)
            {
                e.load_this();
                e.getfield(getFieldName(i));
                e.load_arg(0);
                e.checkcast_this();
                e.getfield(getFieldName(i));
                EmitUtils.not_equals(e, parameterTypes[i], fail, customizers);
            }
            e.push(1);
            e.return_value();
            e.mark(fail);
            e.push(0);
            e.return_value();
            e.end_method();

            // toString
            e = ce.begin_method(Constants.ACC_PUBLIC, TO_STRING, null);
            e.new_instance(Constants.TYPE_STRING_BUFFER);
            e.dup();
            e.invoke_constructor(Constants.TYPE_STRING_BUFFER);
            for (int i = 0; i < parameterTypes.length; i++)
            {
                if (i > 0)
                {
                    e.push(", ");
                    e.invoke_virtual(Constants.TYPE_STRING_BUFFER, APPEND_STRING);
                }
                e.load_this();
                e.getfield(getFieldName(i));
                EmitUtils.append_string(e, parameterTypes[i], EmitUtils.DEFAULT_DELIMITERS, customizers);
            }
            e.invoke_virtual(Constants.TYPE_STRING_BUFFER, TO_STRING);
            e.return_value();
            e.end_method();

            ce.end_class();
        }

        private String getFieldName(int arg)
        {
            return "FIELD_" + arg;
        }
    }

}
